This submission spans my work undertaken over the course of recent years on sub-clinical narcissism, Machiavellianism, and sub-clinical psychopathy: the Dark Triad of personality. Across this thesis, I present a series of published and unpublished materials that cover these overlapping yet distinct personality traits in relation to their attractiveness to women, short- and long-term mating preferences, broader personality and lifestyle correlates, general and sexual competitiveness (in women), verbal and non-verbal behavioural outcomes in a mate-attraction scenario, and health-related behaviours and longevity. I also apply a form of scale analysis to establish how well these traits are measured across sex and age groups by a short inventory that has seen widespread use in the field. Broadly, I consider these issues against a backdrop of evolutionary psychology, individual differences in personality, sex- and age-related differences, and the perception and measurement of personality traits. Specifically, I consider the need to look beyond self-reports, especially when over-claiming is a serious risk, to simultaneously evaluate sex similarities, as well as sex differences, to develop an understanding of the particular behaviours that are demonstrated by individuals with personalities associated with higher levels of mating success, and the need to subject inventories to rigorous scrutiny, across both classical, and item response testing. In each chapter, I have sought to contribute to the on-going discussions that researchers active in this field are engaged with regarding the future of this rapidly-advancing area of study. Interest in this personality constellation shows no sign of abating – its rise to prominence within evolutionary and personality psychology to date has been swift – and I conclude with thoughts and suggestions as to which areas future research could explore in order to further our understanding of the Dark Triad.